As Daniel Oberhaus explains for Motherboard, time-translation symmetry is the reason why it would be impossible to flip a coin at one moment and have the odds of heads or tails at 50/50, but then the next time you flip it, the odds are suddenly 70/30.

But certain objects can break this symmetry in their ground state without violating the laws of physics.

Consider a magnet with a north and a south end. It’s unclear how a magnet ‘decides’ which end will be north and which will be south, but the fact that it has a north and a south end means it won’t look the same on both ends – it’s naturally asymmetrical.

Another example of a physical object with an asymmetrical ground state is a crystal.

Crystals are known for their repeating structural patterns, but the atoms inside them have ‘preferred’ positions within the lattice. So depending on where you observe a crystal in space, it will look different – the laws of physics are no longer symmetrical, because they don’t apply equally to all points in space.

With this in mind, Wilczek proposed that it might be possible to create an object that achieves an asymmetrical ground state not across space, like ordinary crystals or magnets, but across time.

In other words, could atoms prefer different states at different intervals in time?